Certain types of 4H-2,3-dihydro-1,3-oxazin-4-one derivatives are described in, for example, Tetrahedron Lett, (33), 2905 (1976), Heterocycles, 17, 298 (1982), Chem. Pharm. Bull., 35(5), 1871(1987).
However, the compounds described in the above publications differ from the compounds of this invention since none of them has a tertiary alkyl or aralkyl substituent on the 3-position, and no mention is made of their herbicidal activity and plant growth regulator activity.
U.S. Pat. No. 5,006,157 discloses 1-(1-methyl-1-phenylethyl)-3-phenyl-1,2,5,6-tetrahydropyridin-2-one derivatives and their use as herbicides. However, 4H-2,3-dihydro-1,3-oxazin-4-one derivatives and their herbicidal activity have not been described at all in the patent description. In addition, it has been found that the compounds disclosed in the patent description are not good enough in herbicidal efficacy and selectivity.